Add Python 3.11 support #71

Job	Run time
build (Python 3.8, Django 2.2)	27s
build (Python 3.8, Django 3.2)	26s
build (Python 3.8, Django 4.0)	28s
build (Python 3.8, Django 4.1)	30s
build (Python 3.8, Django 4.2)	31s
build (Python 3.9, Django 2.2)	30s
build (Python 3.9, Django 3.2)	32s
build (Python 3.9, Django 4.0)	27s
build (Python 3.9, Django 4.1)	24s
build (Python 3.9, Django 4.2)	33s
build (Python 3.10, Django 3.2)	31s
build (Python 3.10, Django 4.0)	29s
build (Python 3.10, Django 4.1)	35s
build (Python 3.10, Django 4.2)	29s
build (Python 3.11, Django 3.2)	35s
build (Python 3.11, Django 4.0)	29s
build (Python 3.11, Django 4.1)	31s
build (Python 3.11, Django 4.2)	30s
build (Python pypy-3.10, Django 2.2)	49s
build (Python pypy-3.10, Django 3.2)	48s
build (Python pypy-3.10, Django 4.0)	51s
build (Python pypy-3.10, Django 4.1)	48s
build (Python pypy-3.10, Django 4.2)	48s
build (Python 3.11, Django qa)	41s
build (Python 3.10, Django main)	37s
build (Python 3.11, Django main)	38s
build (Python pypy-3.10, Django main)	1m 11s
	16m 8s

Provide feedback